WO2012035531A1

WO2012035531A1 - Sealed and bendable catheter

Info

Publication number: WO2012035531A1
Application number: PCT/IL2011/000686
Authority: WO
Inventors: Eyal Peleg
Original assignee: Vital View Ltd.
Priority date: 2010-09-19
Filing date: 2011-08-25
Publication date: 2012-03-22
Also published as: GB2483735A; GB201103817D0

Abstract

A tubular frame member of a catheter having an articulating segment provides for conveniently bending the catheter within at least one deflecting plane. Enclosing sheath and an optical widow and/r lens provide for sealing the lumen of the catheter off body fluids. The articulating segment is characterized with spaced apart vertebras symmetrically disposed relative to the axis of the tubular frame member. Transverse slits each of which has a pair of longitudinal slits disposed at each of their both ends separate between adjacent vertebras. The spacing disposed adjacent to each end of a vertebra provides for conveniently deflecting the vertebra relative to the axis of the frame member by inducing plastic deformation onto segments and extensions of the axial shafts connecting between coplanar vertebras.

Description

SEALED AND BENDABLE CATHETER

FIELD OF THE INVENTION The present invention relates in general to bendable catheters. In more particular the present invention relates to catheters having a rigid and tubular frame member that has an articulating segment that comprises spaced apart vertebras as well as an optical window or a lens and an external sheath for sealing the lumen of the catheter off body fluids.

BACKGROUND OF THE INVENTION

Cutting a plurality of axially aligned slits that are azimuthally extending in an arc partway around the axis of a catheter thereby providing the catheter with laterally bending capability is known. For example in US patent 7,637,903 a catheter having an articulating segment providing for simultaneously bending the catheter in different planes is disclosed. The articulating segment of the disclosed catheter has one or more sets of pairs of slits. The slits of a pair are diametrically opposed to each other. Successive slits of a set are axially offset. In a case in which the axial offset of slits of one set is of ninety degrees relative to the slits of the other set, bending the catheter in two perpendicular planes can be accomplished.

It is an object of the present invention to provide tubular frame member having an articulating segment for a catheter. The articulating segment provides for bending the catheter in at least one plane. Furthermore, it is an object of the present invention that the provided tubular frame member is cost effective, simple to implement and convenient to use. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an elevational view of a segment of a tubular frame member of a sealed and bendable catheter according to an embodiment of the present invention;

Fig. 2 is an isometric view of a segment of an articulating segment of the tubular frame member shown in Fig. 1 ;

Fig. 3 is an isometric view of a segment of an articulating segment of a tubular frame member of a sealed and bendable catheter according to a preferred embodiment of the present invention;

Figs 4 - 5 are respective elevational view and isometric view of a pair of coplanar vertebras of the articulating segment shown in Fig. 3;

Fig. 6 is an isometric view of a segment of an articulating segment of a tubular frame member of a sealed and bendable catheter according to another preferred embodiment of the present invention;

Fig. 7 is an isometric view of a segment of an articulating segment of a tubular frame member of a sealed and bendable catheter according to another preferred embodiment of the present invention;

Fig. 8 is a scheme of an endoscope incorporated with a catheter of the invention having an articulating segment as is shown in Fig. 6;

Figs 9 - 10 are sectional views of the articulating segment of the endoscope shown in Fig. 8 respectively made across two different planes;

Fig. 11 is a scheme of a sealed and bendable catheter according to a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PRESENT INVENTION

Catheters of the present invention include an articulating segment that provide for non-elastically bending their distal end within one or more rotating planes. Additionally, catheters of the present invention are such sealed that any body fluids cannot get into their lumen. Furthermore, fluids such as liquid or gases cannot get off the lumen of the catheter, unless such fluids are first filtered by means of a hydrophobic filter. Therefore there is no need to sterilize any member that is normally introduced into the lumen of the catheter. Exemplary are the optical fibers that normally provide for illuminating as well as for imaging while the catheter is introduced into, and propagated through, the lumen of internal cavities disposed within the body of a patient. Catheters of the invention have a relatively thin tubular frame member in which an articulating segment is structured. Therefore these catheters are especially suitable to be introduced into, and propagated through, relatively narrow passageways. The articulating segments of catheters of the invention are especially adapted and arranged to be pre-shaped to assume desired curvatures prior to the introduction of a catheter of the invention into targeted passageways.

Reference is first made to Figs 1 - 5. In Fig. 1 a tubular frame member of a sealed and bendable catheter according to an embodiment of the present invention is shown. Articulating segment 10 disposed at the distal end of tubular frame member 12 provides for deflecting the distal segment of the frame member considered by deflection angle 13. Deflection angles are measured according to the invention relative to the axis of tubular frame member 12. A segment of articulating segment 10 is shown in more details in Fig. 2. Transverse slits 14 each of which extends along an arc partway around the axis. The arc of various articulating segment 10, such that semi circular vertebras such as vertebras 16, or 16' interleave between any pair of successive slits 14, or 14" respectively. Spacing of a predefined width separates between adjacent vertebras 16, or 16". Longitudinal slits 18, 18' are axially disposed according to the present invention at both ends of each of transverse slits 14 and 14' respectively. The ends of the longitudinal slits extend beyond the margins of the respective transverse slit towards both sides. Successively arranged longitudinal slits 18, with longitudinal slits 18' collectively form axial shafts 20 that are symmetrically disposed at both opposing sides of articulating segment 10. In Fig. 3 a segment of an articulating segment of a tubular frame member of a sealed and bendable catheter according to a preferred embodiment of the present invention is shown. Each of the transverse slits gradually gets wider towards both ends of the slit considered. The width of a transverse slit reaches its maximal level at the point in which it is connected to the respective longitudinal slit. The rate by which a spacing generated by a transverse slit gets wider, the widths of the transverse slits measured at mid-points, the widths of the vertebras, as well as the dimensions of the longitudinal slits are selected according to the present invention in consideration with the magnitude of the maximal angle by which one circular ring can be inclined relative to its closest neighboring ring. Normally care should be taken not to exceed curvature levels that comply with the limits imposed by any member that has to be introduced into, and threaded through, the frame member considered. For example fiber-optic bundles of an endoscope that might be employed, are normally characterized with radii of maximal curvature that directly imply on the level of maximal inclination angle between adjacent rings of the articulating segment considered.

The present invention concerns cases in which bending the distal end of the frame member within a deflecting plane towards both sides of the axis at the same inclination levels can be accomplished. Therefore symmetrical arrangement of the slits and vertebras and the even distribution of the various dimensions as described above are especially suited for such cases. The main concern of the present invention is catheter having a relatively small diameter of a few millimeters. Following are typical dimensions of the slits and vertebras of an articulating segment such as the one shown in Fig. 3. Such structured and W 201

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arranged slits and vertebras provide for symmetrically bending the frame member relative to its axis within a selected deflecting plane. (Lengths are measured in units in which one unit equals the length of the diameter of the frame member considered.) Width of vertebra 22 ranges between a few tenths to about the full length of the diameter; the length 24 of a longitudinal slit ranges between 0.25 to one full length of a diameter; the width of a transverse slit 26 is of a few hundredths up to about a fifth of the length of a diameter; The full width of a transverse slit measured at the point of maximal width 28 ranges between a number of hundredths of millimeter (mm) to a fifth of the length of a diameter; the width of longitudinal slit 30 ranges between a few hundredths of mm to a third of the diameter; the width of axial shaft 32 ranges between a few hundredths to a quarter of the diameter; and the width of stem 34 ranges between 0.2 to 0.7 of a length of a diameter. The widths of the transverse slits are such selected according to the present invention that a desired maximal bending angle exists between adjacent vertebrae. Obviously wider slits provide for larger bending angle and a smaller radius of curvature.

A pair of coplanar and diametrically opposed vertebrae forms a circular ring that is connected to two opposing axial shafts. In Figs 4 - 5 elevational and isometric views of such ring are respectively shown. Stems 38 respectively connect between both ends of a vertebra and each of the respective segments 20' of the axial shafts. Segments of the axial shaft 20 such as segment 20' are referred hereinafter as bridges. The length that is axially measured along a bridge separating between two adjacent rings is referred hereinafter as the length of the bridge. The width of a bridge is the respective transverse dimension of the bridge. (The thickness of the bridge equals the thickness of the wall of the tubular frame member.) Similarly the length axially measured along a stem is referred hereinafter as the width of the stem. Symmetrical stems 38, 38' as well as segments 20' collectively provide for connecting vertebra 16 to vertebra 16' that is disposed at the opposite side of axial shafts 20. Azimuth angle 40 spans the full length of a vertebra. Doted line 42 indicates the line of intersection of the deflecting plane (which is perpendicular to the plane of the paper of the referenced drawings) and the plane of the circular ring. An articulating segment such structured and arranged provides for bending the distal end of frame member 12 in one deflecting plane; say the plane of the paper of the referenced drawings, as known. The material from which a tubular frame member having an articulating segment is made of, the thickness of its sidewall, the widths and the lengths of the bridges connecting between adjacent vertebrae and/or the lengths and widths of the stems are such selected according to the present invention that bending the bridges and/or the stems for deflecting the articulating segment is effected by means of a plastic (non-elastic) deformation. The yield strength of a shaft made of a given material is the upper limit of the magnitude of the generated stresses above which this shaft starts to be plastically deformed. For a given material and thickness of such shaft, as the width of the shaft gets lower the respective yield strength while bending the shaft within the plane across which this width is measured similarly gets lower. For a given material from which the tubular frame member is made of and a given level of thickness of its sidewall, the dimensions of the bridges (lengths and widths) of the articulating segment of this tubular frame member, and/or the dimensions of its stems, are such selected according to the present invention that the respective yield strength stresses generated while the articulating segment is deflected does not exceed a predefined value, which is-lower compared to the respective yield strength. Namely, such stresses exerted onto the articulating member, their magnitudes exceed this predefined level will result in nonelasticly deforming yield strength.

An exemplary cylindrical frame member is made of stainless steel. It has a diameter of 1.5 millimeters (mm) and the thickness of its sidewall is about 0.1 mm. Slits having shapes and dimension as described above with reference to Fig.3 are structured and arranged to form such articulating segment. Cutting the slits is accomplished as known. Preferable is laser cutting that enables the various shapes and margins of the slits such as described hereinabove quite easily at affordable costs. One may quite easily manually twist and deform by plastic deformation the respective bridges and/or stems of the articulating segment of this exemplary frame member. Such deforming is accomplished by means of one's fingers to bend the articulating segment laterally with respect to the axis of the tubular frame member within the deflecting plane. The inventor W

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of the present invention, has personally experienced that in cases in which the frame member is either enclosed, and/or is not enclosed, within a tubular sheath made of polyethylene, such bending is easily accomplished. Flexible sheathes made of any other flexible materials such as materials that are normally utilized for manufacturing cannulas for medical use, similarly provide for such bending. Namely suitably deforming at least a number of bridges and/or stems of the articulating segment by means of the fingers of a user can be easily accomplished. Furthermore, pulling such deformed and deflected frame member off such elastic sheath is involved with its being straightened up back into its original cylindrical form. The plastic deformation that causes the straightening of the articulating segment is automatically effected by strains exerted unto the deflected articulating segment by the twisted sidewall of the flexible sheath while the bended segment of the frame member is released and gets off the sheath. Alternatively, pull wire can be used to deflect and/or straighten up the distal end of the tubular frame member, as known. Pull wires are attached to the outermost distal vertebras as known. Each pull wire is threaded across a vertebra its wall is pressed below the span of the radius of the frame member. First, the wall of every, say forth vertebra 50 disposed along segment 52, shown in Fig. 6, is inwardly bended. Such bending results in apertures disposed at both sides of vertebra 50 that are opened into the lumen of the frame member considered. These apertures provide for threading pull wire 54 through. The number of vertebras 56 that are not such deformed need not be four but can be any selected number as desired. Reference is now made to Fig. 7 in which a segment of an articulating segment of a tubular frame member of a catheter according to another preferred embodiment of the present invention is shown. Articulating segment 60 includes two sets of pairs of vertebras as described hereinabove. The first set designated by 62 consists of batches of vertebras grouped together in coplanar pairs each of which includes two vertebras symmetrically disposed at two opposing sides of the axis of the tubular frame member considered. All the vertebras disposed at the same side of the axis span the same azimuthal range and each of its endpoints has the same azimuth angles. The other sets designated by 64, consist of similarly grouped vertebras except that their endpoints are axially offset by a predefined azimuth angle. Therefore this articulating segment provides for deflecting the distal end of this tubular frame member in two different deflecting planes that intersect each other at this predefined angle, as known.

EXAMPLE 1

Cylindrical tubular frame member such as described hereinabove (its diameter is of 1.5 mm and its wall thickness is of 0.1 mm) is made of stainless steel of the following mechanical properties-, mass density of 8000 killograms/meter³; elastic modulus of 1.9^*10¹¹ Newton/meter² (N/m²); yield strength 2.0681 *10⁸ N/m². The geometrical shapes and dimensions of the longitudinal and transverse slits to be structured along the sidewall of the articulating segment of this tubular frame member are such selected that a predefined magnitude of the maximal bending angle is achieved when is deflected in one deflecting plane such that the slit separating between two adjacent rings closes down at one side of the articulating segment. (Two adjacent vertebrae mutually touch each other when such closing down occurs while the articulating segment is deflected.) For selecting the dimensions of the bridges and/or the stems of this articulating segment according to the present invention a mechanical strength analysis is carried out. Any computer program for computing mechanical strength analysis that is commercially available can be employed. Exemplary is the computer program that is typically included in a tool kit of for example the commercial CAD program named SolidWork^(R). Alternatively any computer program for mechanical strength analysis employing finite elements technique that is commercially available is suitable for this purpose. By selecting for example the dimensions of the bridges of the articulating segment to be of 0.3 mm width, and of 2 mm length, and simulating the bended adjacent rings by a desired bending angle, say of a magnitude that equals the maximal bending angle, the maximal level of stress that is generated within the bridge while is bended to give this aforementioned bending angle, as is reflected by such mechanical analysis is 5.8*10¹⁰ N/m². This value exceeds by far the yield strength of these bridges. Therefore for such selected dimensions of the bridges of the articulating segment considered a user may plastically deform them while bending the articulating segment.

EXAMPLE 2

Tubular frame member having an articulating segment such as of frame members of catheters of the invention can be incorporated with endoscopes, especially suited to be introduced into relatively narrow passageways within mammalian bodies. Reference is now made to Figs 8 - 10. In Fig. 8 endoscope 70 having a tubular frame member including articulating segment as described hereinabove is shown. Tubular frame member 72 is cylindrically shaped. Tubular frame member 72 has a diameter of 1.5 mm and the thickness of its wall that is made of stainless steel is 0.1 mm. Articulating segment 74 that is disposed at the distal end of tubular frame member 72 provides for deflecting its distal end within at least one plane. Lever 76 provides for selectively moving pull wires through tubular frame member 72 thereby deflecting and/or straightening the distal end within at least a single plane. Eyepiece 78 provides for viewing images received and delivered by means of imaging fiber bundle, not shown, that is threaded through the tubular frame member. Connector 80 provides for connecting illuminating source to an illuminating fiber bundle, not shown, for illuminating the region distally disposed relative to the distal end of the tubular frame member. Gas inlet 82 provides for delivering oxygen, or air enriched with oxygen into the lumen of the tubular frame member. Connector 84 provides for fluid connecting gas inlet 82 to sources of insufflating gases.

In Figs 9 - 10 sectional views made across planes AA and BB shown in Fig. 8 are shown. Plane AA separates between two rings that are not deformed for threading the pull wires across their surfaces. Plane BB is positioned adjacent to a ring that is deformed for threading the pull wires off and into the lumen of the tubular frame member. Distal end of tubular frame member 90 has sidewall 91 that encloses imaging fiber optic bundle 92, illuminating fiber bundle 94, and pull wires 96. The deformed ring 98 encloses both fiber optics bundles whereas the pull wires are disposed exterior to the volume enclosed by sidewall 99. Such endoscope is suitable for insufflating premature babies especially in cases in which insufflating is accomplished even along the process of introducing the tubus into the airways of the baby. The tubular frame member of the endoscope has a diameter that does not exceed the inner diameter of the tubus considered. The frame member of the endoscope is provided with articulating segment of one deflecting plane. First the tubular frame member is inserted into the tubus which is made of flexible material. Shaping the distal segment of the endoscope such that it will comply with the curvatures along the airways of the baby is manually accomplished by means of the fingers of the care providing personnel member prior to the insertion of the tubus. There is no need for special channel that is dedicated for delivering an insufflating gas through the endoscope considered. Therefore the width of the frame member can be minimized such that it is suited for introduction through relatively narrow passageways, such as the trachea of a premature baby. The spacing that exists between the electro-optical bundles, the pull wires and the inner surface of the tubular frame member provides for fluid connection that is sufficient for delivering the insufflating gases.

EXAMPLE 3

Endoscope such as described in EXAMPLE 2 above can be employed for guiding standard embryo insertion catheter to enter the patient's Uterus. First the frame member of the endoscope is introduced into a sheath the lumen of which is adapted and arranged for guiding standard embryo insertion catheter. The inlet for insufflating gas of the endoscope is connected to a source of air enriched with CO₂ gas, at the same concentration typically utilized for an ambient atmosphere of incubators. Common Hystero - insufflator connected to balloons respectively containing C0₂ and sterilized air and a gas W

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blender can be employed for implementing such source as known. Then the articulating segment of the endoscope is pre-shaped to have the suitable curvatures. The insufflating with air enriched with CO2 is carried out along the process of introducing the sheath into the uterus. Such insufflating provides for opening passageway through the cervix, through which the sheath enclosing the endoscope is propagated. Care must be taken not to exceed the pressure of the insufflating gas such that air is not permitted to get into the blood circulation of the patient as known. The introduction process continues until the tip of the endoscope reaches the exact location within the uterus in which the embryo has to be placed. When the desired location has been reached the endoscope is pulled off and is substituted with the embryo insertion catheter. A relatively stiff proximal segment of the sheath provides for straightening up the bended end of the frame member while is pulled off the sheath.

EXAMPLE 4

The endoscope described in both examples 2 and 3 hereinabove as well as the frame member considered have to be sterilized prior to the introduction of the fiber optic bundles into the frame member. Reference is now made to Fig. 11 in which a scheme of a sealed and bendable catheter according to a preferred embodiment of the present invention is shown. Catheter 110 includes frame member 112 that has articulating segment 114 which is similarly structured such as was described in example 1 hereinabove. Plastic sheath 116 tightly encloses the external surface of the sidewall of frame member 112, such that the slots of articulating segment 114 are fully covered and the lumen of frame member 112 is sealed off the ambient of the distal end of catheter 110. Furthermore a transparent member 118 is tightly attached at the distal end of frame member 112, such that it seals off the distal aperture of the tubular frame member. Optical window and/or a suitable lens implement such transparent member according to the present invention. Therefore body fluids that might be present nearby the distal end of catheter 110 cannot get into its lumen. Similarly, any fluid that might be present within catheter 110 cannot leak out of the distal segment of catheter 110 into the body cavity in which it is introduced and/or progressed through. Connector 122 disposed at the proximal end of catheter 110 provides for connecting the catheter to say an endoscope, such as by introducing the respective bundles of optical fibers for illuminating and imaging through the lumen of tubular frame member 114, This lumen is isolated from inner volume of space 123 of connector 122. Hydrophobic filter 124 disposed within this volume provide for sterilizing fluids or gases that can be introduced by means of connector 122 through aperture 126 into the lumen of enclosing canola 128. Flanges such as flange 130 provides for conveniently connecting catheter 110 to the endoscope and a source of insufflating fluid, not shown.

Claims

1. A sealed and bendable catheter having a tubular frame member which includes an articulating segment, wherein said articulating segment has an axis and a plurality of vertebrae symmetrically disposed relative to said axis along said axis, said sealed and bendable catheter comprising a sidewall such structured and arranged that the yield strength of at least one segment of which does not exceed a predefined level, wherein a first transverse slit separates between both vertebrae of at least one pair of said plurality of vertebrae, which is the first pair of said plurality of vertebrae, and wherein each vertebra of said first pair positioned at the same side, which is the first side relative to said axis, and wherein a second transverse slit separates between both vertebrae of another pair of said plurality of vertebrae, which is the second pair of said plurality of vertebrae, each vertebra of the second pair positioned relative to said axis at the side opposing the first side, and wherein stems respectively connect between the ends of respective vertebrae of said first and second pairs of vertebrae and two axial shafts which are symmetrically positioned along said articulating segment.

2. A sealed and bendable catheter as in claim 1 , wherein said at least one segment of sidewall comprises a bridge.

3. A sealed and bendable catheter as in claim 1 , wherein said at least one segment of sidewall comprises a stem.

4. A sealed and bendable catheter as in claim 1 , further comprising a transparent member for sealing off the distal aperture of said tubular frame member, wherein a sheath enclosing said tubular frame member further seals off said transverse slit.

5. A sealed and bendable catheter as in claim 4, wherein said transparent member is a lens.

6. A sealed and bendable catheter as in claim 4, wherein said transparent member is an optical window.

7. A sealed and bendable catheter as in claim 4, further comprising a connector disposed at the proximal end of said tubular frame member, and wherein a hydrophobic filter housed within said connector.

8. A sealed and bendable catheter such as in claim 1 , further comprising at least one longitudinal slit, disposed at an end of said transverse slit, and wherein said at least one longitudinal slit directed along said axis, wherein each end of said at least one longitudinal slit extends away from a margin of said transverse slit.

9. A sealed and bendable catheter such as in claim 1 , and wherein said transverse slit extends along an arc partway around said axis.

10. A sealed and bendable catheter such as in claim 1 , wherein the width of said at least one transverse slit measured at a point disposed close to an end of said transverse slit is larger compared to the width of said at least one transverse slit measured at a midpoint of said transverse slit.

11. A sealed and bendable catheter such as in claim 1 , wherein a segment of one of said two adjacent vertebras inwardly bended, such that any point disposed across said segment of one of said two adjacent vertebras is closer to the axis of said articulating segment compared to points disposed close to the ends of one of said two adjacent vertebras.

12. A sealed and bendable catheter such as in claim 7, wherein the lumen of said connector fluid connected to a source of insufflating gas.

13. A sealed and bendable catheter such as in claim 12, wherein said insufflating gas comprises a gas selected from a group of gases consisting of air, oxygen, air enriched with oxygen, C0₂, air enriched with C0₂ and any combination thereof.